Compensation device for torsional pendulums.



No. 868,264. PATENTED 00T. 15, 1907. C. E. GUILLAUME.

COMPENSATION DEVICE FOR TORSIONAL PENDULUMS. unroulox rus nov. 1. 1905.

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nu: Nomifs pzrsns cal, vusnmcrav CHARLES EDOUARD GUILLAUME, OF SVRES,FRANCE.

COMPENSATION DEVICE FOR TORSIONAL PENDULUMS.

specification of Letters Patent.

Patented Oct. 15, 1907.

Application filed November 1,1905. Serial No. 285,492.

To all whom it may concern:

Be it known that l, CHARLES EDOUARD GUILLAUME, a citizen of the Republicof Switzerland, residing at Svres, Department of Seine-et-Oise, France,have invented improvements in or Relating to Compensation Devices forTorsion-Pendulums, of which the following is a full, clear, and exactdescription.

'lhis invention relates to compensation devices for torsion pendulums.

Clockwork mechanisms in which, as heretofore, the regulator or balanceconsists of an oscillating mass, moving to and fro in a horizontalplane, suspended from the end of a suspension thread, band or strip andreturned by this latter to the position of equilibrium, are exceedinglysensitive to the action of the temperature, and experience, -under theinfluence of heat, considerable variations in the periods of oscillationowing to the actions set up by variations in the modulus of torsion ofthe said suspension thread and owing to the expansion of the oscillatingmass. The expansion of the suspension thread on strips produces aninverse effect, the value of which, however, is small as compared withthe sum of the actions previously referred to.

Experiments in connection with the alterations of the modulus of torsionunder the influence of the temperature in the case of certain alloys,which contain chiefly' iron and nickel, have demonstrated that, contraryto what is the case with the metals or alloys ordinarilyr employedhitherto, the modulus of torsion increases with the temperature, whenthese alloys contain a certain percentage of nickel (30 to 46% parts byweight), as will be said more precisely further on.

The present invention is based upon this peculiar phenomenon. Broadly itconsists in forming the suspension thread, band or band-like strip of anappropri-ate alloy of iron and nickel, this alloy being such as torender possible a compensation of the alterations in the period ofoscillation of the pendulum mass caused by the action of thetemperature.

By reason of the effect of the expansion of the band or strip and thatof the oscillating mass, referred to above, this compensation isobtained by forming the.

suspension thread, band or strip not of an alloy whose modulus oftorsion remains absolutely constant at varying temperature, but of analloy whose modulus of torsion exhibits slight positive or negativevariations, and selected in such manner that the sum of the threeeffects enumerated approximates as closely as possible vto zero. Thiscondition is attained by forming the thread, baud or strip of an alloywhich does not contain exactly 30% or 46% of nickel, but percentagesvarying slightly therefrom. Obviously with similar alloys the going ofthe clock will be considerably improved with varying temperatures, ascompared with the suspension devices ordinarily employed; absolutecompensation will not be attained closer than certain limits.

ln the accompanying drawing forming a part of this application, Figure lis a iront elevation of one form of my improved pendulum. Fig. 2 is aside elevation of the same. Fig. 3 is a front elevation of a portion ofthe pendulums illustrating a modified form, and Fig. 4 is a sideelevation thereof.

Referring to Figs. l and 2, the body or weight a is suspended to thelower extremity of a metal rod b which forms the pendulum, said bandfastened at its upper end at c, and made of a suitable alloy of iron andnickel in accordance with the invention set forth, the modulus oftorsion of said pendulum b when suitably formed, being adapted toincrease, to compensate for the relative expansion of the said pendulumand the body or weight u.

As shown in Figs. 3 and 4, the upper portion d of the pendulum consistsof a rod of nickel-steel, the modulus of torsion of which increases inproportion as above described. At the end of said first part 2 isfastened the second part g ofthe pendulum by means of the Clampingplates e, c and screws f, f, said second part being made of`a metal oralloy, the modulus of torsion of which decreases when the temperaturerises, the said parts d and g effecting in combination a changingmodulus of torsion compensating for the expansion of the same and theweight hung at the lower end thereof. The portions d and g are, by theconnecting means shown, capable of relative adjustment, and thereforemay be reset, if, after observations of the clock it is found thatcompensation has not been perfectly-obtained in the first instance.

Experience has` demonstrated that in accordance with the presentinvention compensation is attainable in all cases that can arise inpractice, if the oscillating mass is formed of any ordinary metal or anyordinary alloy, and the suspension thread, band or band-like strip of analloy of iron with an addition of nickel varying between the limits of29 and 32% on the one hand and 45 and 48% on the other hand, of theweight ofthe alloy. It is not necessary that these alloys should beproduced in a laboratory, that is to say they need not be chemicallypure g on the contrary they maybe ordinary commercial alloys containingsmall quantities of the case in the metals as extracted. An admixturetherewith of chromium increases the torsional resistance of thesuspension devices, that is to say the thread, band or band-like strip.lf such an addition be made, the percentage of iron and nickel should bereduced carbon, manganese, silicon and the like, as is usually somewhat,in such manner that with the -rst group of alloys the percentage ofnickel is increased, and in the second group it is decreased. In thepresent case, however, it is only a question of slight difference in thepercentages, as any considerable admixture of chromium would render thealloys difficult to work.

When one ofthe alloys above referred to is employed,

the process and means constituting the present invention permit ofobtaining absolute compensation.

The table given below shows the dependence of the modulus of torsionupon the temperature and upon the alloy A Variation of the tor- Theseiigures relate to ordinary temperatures. As, however, in the case oi allalloys with a high percentage of nickel, the alteration with thetemperature' is practically constant, these gures are also applicable totemperatures differing within reasonable limits from the normal. In thecase oi alloys containing a low percentage, on the other hand, theco-efiicient changes somewhat rapidly, tending, with a risingtemperature, towards a more negative value.

An addition oi chromium imparts to the co-efllcients a more constantvalue and therefore' maintains the compensation within wider limits.'

In order to allow for any defect in the property oi the thread, it isadvisable to form the suspension thread, band orv strip of two parts,one only oi which consists of Anickel steel, whose modulus of torsionincreases with rising temperature in accordance with what has beenstated above. By suitably selecting the lengths and cross section oi thetwo parts ofthe suspension strip, it is possible to obtain compensationfor' the alterations in the conditions of the one by the alterations inthe other', in combination with the alterations in the moment of inertiaof the oscillatingr mass caused by the temperature.

The two parts of the suspension means are either soldered or rivetedtogether or `connected one with the other in any other appropriatemanner. A very suitable means is to attach the two parts one to theother by means oi an ordinary clip or clamp permitting oi altera-Y tionsin the length oi the thread, band or strip. In the rst it isadvantageous to adjust the two parts of the suspension means to aconsiderable length7 which is reduced towards one side or the other ifobservations oi the clockwork show that the compensation has not beenattained on the iirst step. This adjusting o1` regulating means is insome instance similar to that employed in watches for the purpose oivarying the effect of the bimetallic bands ofthe balance.

Owing to its extreme simplicity, the rst device is preferably employedin" the case' of works oi medium quality; it permits oi slightalterations in the period oi oscillation: ot the moving parts atdifferent temperatures. The second device is more exact in its operationand is the preferred form for use in precision clocks in which it fullycompensates for variations oi the temperature.

The suspension means may likewise consist oi more than two parts; thedimensions oi this means and its various parts may vary as desired.

Having now particularly described my invention, I claim as new and wishlto secure by Letters Patent:-

l. A torsion pendulum comprising` a weight and means for supporting saidweight, aportion of said supporting means having a modulus of torsionthe value of which increases correspondingto the temperature tocompensate for the expansion of`said entire supporting means and saidweight, substantially as described.

2. A torsion pendulunr comprising a Weight and means for supporting saidweight, a portion of said supporting means being constructed of an alloyof' iron and nickel and having a modulus ofY torsion the value'of whichincreases corresponding to the temperature to compensate for theexpansion of'said entire supporting means and said weight, substantiallyas described.

3. Ina torsion pendulum, a pendulum rod, comprising two relativelyadjustable rods fastened one to the other, and a weight' carried by theend of the lower rod, one of said rodsv having a modulus of torsion thevalue of which increases corresponding to the temperatureto compensatefor the expansion of said weight and both of said rods, substantially asdescribed.

41 A torsion pendulum comprising a weight and' means for supporting saidWeight, a portion of said supporting means having a modulus of torsionthe value of which increases corresponding to the temperature tocompensate for the expansion of said entire supporting means and saidweight, and being constructed of an alloy of 72 to 64 parts of iron, 28-to 3l parts of nickel, and 5 parts of arare earth, substantially asdescribed.

5. A- torsion pendulum comprising a weight and means for supporting saidweight, a portion of said supporting means having a modulus of torsionthe value of which increases corresponding to thel temperatureA tocompensate I for the expansion of said entire supporting means and saidweight, and being constructed of an alloy of 7,2 to 69 parts of iron and'28 to 31 parts ofnickel, substantially as described.

G. In a torsion pendulum, a pendulum rod consisting of two bandsfastened one tothe other, and one of which has a modulus of torsion, thevalue of which increases corresponding to the temperature.

7. In a torsion pendulum, a pendulum rod consisting of two bandsfastened one to the other, and one of which has a modulus of torsion,.the value of which increases cor respondingr tothe temperature, saidrod being made of an allo;7 containing. 72 to 50 parts of iron, 28 to 50parts of nickel and 5 parts of a rare earth.

8. In a torsion pendulum, a pendulum ro'd consisting of two relativelyadjustable bands fastened one to the other,

and` one of which has a modulus of torsion, the value of which increasescorresponding to the temperature.

In testimony whereof I ainx my signature in presence of two witnesses.

V CHARLES EDOUARD GUILLAUME.

Witnesses HANsoN C. Coxn, PIERRE Gunn.

